Method for forming glass containers

ABSTRACT

Method for forming glass containers by the blow and blow process in which a parison mold having a plurality of cavities is centrally positioned relative to a pair of blow molds having a plurality of cavities. The parisons are formed with their necks down in the parison mold from a charge of glass delivered to each cavity. Vacuum is applied to the neck area of the mold to form the finish portion of the container. A neck pin is pulled and air under pressure is fed to the interior of the area from which the neck pin is drawn to expand the glass within the parison mold at a continuous rate until the glass within the parison mold comes in contact with a baffle which closes the upper end of the parison mold. The parison mold is then opened and the parisons are transferred alternately from the parison mold to the blow molds where they are expanded into final shape. During the transfer of the parisons from the parison mold to the blow mold, air under pressure is maintained within the hollow interior of the parison. The parison transfer is carried out by the neck molds with parison counterblow pressure delivering means as well as puff or low pressure means for either puffing the parison during its invert movement from the parison mold to the upright position at the blow mold or to help sustain the parison against collapse during invert. The ability to apply puffing air to the parison during transfer is a significant step in the forming process.

BACKGROUND OF THE INVENTION

This invention relates to the manufacture of blown glass articles suchas bottles, jars, flasks, etc. According to the "narrow neck" or "blowand blow" method presently used and as described in U.S. Pat. No.1,911,119, a charge of glass is delivered to and compacted or caused tosettle in the cavity of an inverted or neck-down blank or parison mold,the glass of the charge extending from the neck portion of the moldcavity part of the way up the sides thereof. A baffle plate is placed onthe uppermost end of the inverted blank or parison mold and air underpressure is applied to the interior of the glass in the mold tocounterblow such glass into conformity with the internal configurationof the blank or parison mold and against the baffle plate. Thereafter,the counterblown blank or parison is transferred to an upright finalblow mold in which the blank or parison is disposed in an upright orneckup position and air under pressure is applied to the interiorthereof. The counterblown blank or parison is thus expanded to theconfiguration of the final blow mold cavity, thereby forming an articleof the final shape and size desired.

This method of forming articles of glassware has been practiced sincethe 1920's. Certain faults and shortcomings have been known and suchdefects as "settle waves" in the sidewalls of the article, marking thejuncture of wall portions of two different thicknesses are common. Othercommon defects are baffle marks and shear scars in the bottom of thearticle. Furthermore, articles of generally circular cross-sectionalconfiguration have experienced the formation of excessively thickbottoms and relatively thin shoulders when produced by theabove-described method. Those articles which would have a generallyrectangular cross-section configuration or are of a flask shape usuallyhave excessively thick sides or panels and relatively thin shoulders. Asa matter of fact, different portions of practically all articlesproduced by the aforementioned method vary substantially in thethickness of the walls thereof. Therefore, for most articles of a givensize and intended use, it has been necessary to use a glass charge ofundue size and weight so as to insure that the article produced will bethick and strong enough at its thinnest wall to enable the article towithstand the normal abuse during the service for which the article isintended. The temperature of the glass from which the article is formedis lower than would be equally suitable if the charge were substantiallysmaller.

An attempt to avoid some of the problems discussed above would appear tohave formed the basis for U.S. Pat. No. 1,840,532 dated Jan. 12, 1932,issued to G. E. Rowe. The general teaching of this patent was, ineffect, that if the making of a bottle could be accomplished withoutforming a parison in a parison mold, then a lighter weight bottle couldbe produced. Whether this patent or the invention set forth therein everbecame commercially significant or was ever actually practiced is notknown to applicants. It is clear that the previously mentioned U.S. Pat.No. 1,911,119, issued to the same assignee, has become the forerunner ofthe presently successful and commercially important standard "I.S."glass forming machine. Thus it would appear that the invention in U.S.Pat. No. 1,840,532 did not prove to be successful or was incapable ofbeing commercialized. One complicating factor that was involved, in theprocess of Rowe, was the rotation of the charge of glass about thecentral axis of the neck mold, in order to attain some semblance of evendistribution of the glass about the bubble that was being blown orformed therein. This would appear to be a closer approach to thehand-blowing techniques where the charge was rotated by the glass bloweron the end of a punty while being expanded.

Some of the shortcomings and faults mentioned above are eliminated ortheir effect is minimized by the present invention which, it will beseen from the detailed description to follow, has some of the steps ofthe well-known, commonly practiced, "blow and blow" process of formingglassware, but will differ therefrom in important particulars.

It has been known that hand-blowing techniques for forming hollowobjects from glass have been capable of producing thin walled articleshaving fairly uniform wall thickness. The hand-blowing technique,however, requires considerable skill and experience and in this day is arelatively unique talent not possessed by many glass producers andcertainly would not be an economically feasible method of producingglass containers of the type that are presently made by machines inlarge volume.

SUMMARY OF THE INVENTION

The method for forming glass containers by the blow and blow processwherein a gob of glass is delivered to a parison and neck mold cavityand the gob is settled in the neck mold by vacuum. After the vacuumsettle has been completed, air under pressure is used to softlycounterblow in the parison mold to thereby form a parison and uponcomplete counterblow of the parison, the parison is inverted andtransferred from the parison mold to a final or blow mold where theparison is expanded into final form. Superatmospheric pressure ismaintained within the interior of the formed parison during the transferand inversion thereof, with the pressure within the parison beingreleased after transfer to the blow mold is completed, resulting in aglass container of a given volumetric capacity being formed with lessglass and of a more uniform wall thickness and improved strength.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a glass forming machine for carrying outthe present invention;

FIG. 2 is a cross-sectional view taken at line 2--2 of FIG. 1;

FIG. 3 id a cross-sectional view taken generally at line 3--3 of FIG. 2with the blow head removed for clarity; is

FIG. 4 is a cross-sectional view on an enlarged scale taken at line 4--4of FIG. 3;

FIG. 5 is a cross-sectional view on an enlarged scale taken at line 5--5of FIG. 1 showing the neck mold and transfer mechanism in detail;

FIG. 6 is a cross-sectional view, similar to FIG. 5, showing the plungeror neck pin in retracted position; and

FIGS. 7-21 inclusive are diagrammatic views illustrating the parison andbottle forming process carried out by the apparatus with a singlearticle formation illustrated.

DETAILED DESCRIPTION OF THE DRAWINGS

The apparatus illustrated in the accompanying drawings, when operated inits intended manner will perform the process of the invention to producearticles of glassware such as bottles and jars which will have veryuniform radial glass wall distribution. The improved radial distributionpermits substantial reduction in glass weight without loss in containerstrength.

Because in the past the counterblow of the parison was carried out withair pressure sufficient to accomplish the delayed counterblow in arelatively short period of time and the glass was blown against the moldwalls and the baffle with considerable force, a significant amount ofheat was conductively removed by the contact of the glass with the moldwalls and baffle. This resulted in the development of a fairly thick,viscous, chilled surface or, as is termed in the art, an enamel or skinthat would provide a degree of stiffness to the parison. This permittedthe parison to be unsupported, in an inverted position, when the parisonmold and baffle were removed from contact with the parison. The parisoncould then be inverted by the transfer means carrying the parison to theblow mold. Obviously, if the skin or enamel of the parison is relativelythick, the reheat period necessary to permit the heat within the parisonto remelt or resoften the skin of the parison must be relatively long.The length of time for completed reheat will slow up the blowing processat the blow station. The reheat must be completed, otherwise the parisoncannot be expanded in the blow mold with any hope of having relativelyeven wall thickness distribution. With poor distribution, the containerwill be only capable of withstanding pressures or abuses that thethinnest section can handle.

With the foregoing in view, the instant process has several distinctadvantages over the present forming processes in that a hotter (25°-100°F.) glass gob of reduced weight may be used. The hotter gob is deliveredto a mold and immediately set in the finish mold by vacuum. The time ofcontact with the mold wall is minimal and the forces involved are thatof gravity except in the neck forming zone. The counterblow is begunimmediately without requiring any significant corkage reheat periodbecause of the elevated glass temperature and short plunger-glasscontact time. The total time of the glass in the parison mold may be 1.6seconds compared to 2.1 seconds in the standard "I.S.". The counterblowpressure is kept at a low level (of about 1 to 10 psi. internally of theparison as compared to about 30 psi. for the standard "I.S." process) soas to create what may be termed a "soft" counterblow. The term "soft",while being synonymous with low pressure, also has another significantconnotation, in that the glass parison is expanded to the extent thatthe mold walls and baffle permit but the glass only very lightlycontacts these surfaces. In other words, the counterblow never resultsin any substantial force with regard to the contact of the parison withthe parison mold. This procedure has the advantage that the heat removalfrom the parison through conduction is reduced. This results in theparison being without a thick skin or enamel of chilled glass. When thisparison is to be transferred from the open parison mold to the blowmold, it requires support of a sort, and in the present process takesthe form of air trapped within the parison that is above atmospheric inpressure. The extent of the pressure of the entrapped air will depend onthe degree of stiffness required to support the parison during invertand transfer. It may even be desirable to inject a "puff" of air underpressure to the interior of the parison to render the parison stiffer orto effect an actual expansion of the parison during transfer.

It has also been determined that one advantage of using hotter gobs andmaintaining the parison wall temperature somewhat elevated above thatcurrently being practiced is that the surface of the article beingproduced, will have less sodium ions after forming and this shouldresult in a glass article having a greater resistance to abrasion andimproved strength characteristics.

With reference to the drawings and in particular to FIGS. 1-3, adescription of the illustrated apparatus will follow. The formingmachine of the invention comprises a generally horizontal table 10 whichis supported at an elevated location above a base 11 by side walls 12and 13 and end walls 14 and 15. The side wall 12, as best seen in FIGS.1 and 3, has a portion which extends outwardly and houses reciprocatingmotors 15. A cover plate 16 is removably attached to the outstandingportion of the wall 12 so as to provide access to the interior of theenclosure formed by the base 11, side walls and end walls and horizontaltable 10. Table 10 supports a parison forming station generallydesignated 17, with a vertical plane 18 defining the split line betweenparison mold halves 19 and 20 being centrally positioned relative to thelength of the table 10 but cross-wise thereto. A pair of blow molds orfinal blow stations, generally designated 21 and 22, are positioned onopposite sides of and equally spaced from the parison forming station17. Blow station 21 is comprised of a pair of blow mold halves 23 and 24and likewise the blow station 22 is comprised of a pair of blow moldhalves 25 and 26. The split line between the mold halves of both blowmold stations 21 and 22 defines vertical planes which are parallel tothe vertical plane 18 defining a split line of the parison mold halves.The parison mold halves are mounted to arms 27 and 28 which extendsubstantially the full length of the parison molds. Intermediate theirlength, the arms 27 and 28 are supported by vertical pivot pins 29 and30. The pivot pins 29 and 30 extend through bushings 31 and 32 in uppercastings 33 and 34 of a "four-bar" linkage which supports the parisonmold halves. The upper castings 33 and 34 extend in a horizontal planeparallel to the plane 18 of the mold halves and at their extreme endsare pivotally mounted within the upper ends of connecting links 35. Theconnecting links 35 extend downwardly and have a somewhat bowedconfiguration with their lower ends being keyed to shafts 36 and 37. Theupper castings 33 and 34 also have a portion which extends outwardly atright angles with respect to the pins 29 and 30 and these portions arebifurcated. Horizontal pivot pins 38 and 39 pivotally connect thebifurcated portions of the upper castings 33 and 34 to the upper ends ofconnecting links 40 whose lower ends are pivotally connected to fixedanchor members 41. The anchor members 41 are mounted to the uppersurface of the table 10.

As can best be seen in FIG. 2, the horizontal axes of the shafts 36 and37 are parallel to the horizontal pivot axis of the horizontalconnections of the links 40 to anchor members 41. The relativedisplacement of these two axes is essentially the same as the effectivelength of the connecting links 33 and 34 between the upper pivot pins 38and 39 and the respective upper ends of the connecting links 35. Thus itcan be seen that the links 35, upper casting 34, link 40 and the factthat the shaft 37 and anchor members 41 are fixed relative to each otherconstitute a "four-bar" linkage which effectively will maintain openingmovement of the mold half 20 in the direction such that the face of themold half 20 generally will be parallel to the plane 18. In the samemanner, the mold half 19 is maintained with its mold face parallel withthe plane 18 when moved relative to the other mold half 20. The blowmold halves 23 and 24 are likewise mounted on arms 42 and 43 with thearms 42 and 43 movable relative to each other by a "four-bar" linkage ofsubstantially identical construction to that which supports parison moldhalves 19 and 20. Similarly, the blow mold halves 25 and 26 are mountedto arms 44 and 45 and they in turn are also supported by "four-bar"linkages of substantially identical construction to that shown forsupporting parison mold halves 19 and 20 and the other blow mold halves23 and 24. In all of the configurations of the mold supporting"four-bar" linkages, the two shafts which correspond to the shafts 36and 37 at the parison forming station are the movement initiating oroperating members. These shafts are driven by fluid motors, one of whichis shown at 46 in FIG. 3.

Inasmuch as FIG. 4 has an enlarged detailed showing of the fluid motor46 of FIG. 3, which when operated will open and close the blow moldhalves 25 and 26, it should be understood that a similar fluid motor ispresent for actuating the shafts 36 and 37 at the parison formingstation 17 and comparable shafts associated with the blow mold station21. The specific shafts associated with the blow mold station 22 areindicated by reference numerals 47 and 48.

With particular reference to FIGS. 3 and 4, the linkage from the fluidmotor 46 to the shafts 47 and 48 will be described. Generally speaking,the shafts 47 and 48 are provided with crank arms 49 and 50. As can bestbe seen in FIG. 4, the crnk arms extend generally downward and thoseportions of the shafts 47 and 48 to which the crank arms are connectedare provided with a cover 51, the purpose of which is to prevent anybroken glass or other material from interfering with the operation ofthe fluid motor. A similar cover is provided at the other stations 17and 21. The motor 46 is pivotally mounted at its upper ends by pins 52and 53 to a downwardly extending fixed support member 54. As shown inFIG. 3, the support member 54 is comprised of two spaced-apart members,both of which are provided with vertically elongated slots 55 withinwhich the ends of a horizontal pivot pin 56 is adapted to ride. Thepivot pin 56 extends through a clevis 57 to which a piston rod 58 of themotor 46 is connected. Thus it can be seen that operation of the motor46 will result in vertical reciprocation of the rod 58 which in turnwill move the clevis 57 up and down. A pair of links 59 and 60 areconnected to the pivot pin 56 at one end and to the crank arms 49 and 50at their opposite ends. In this manner, reciprocation of the piston rod58 results in the oscillatory, rotational motion of the shafts 47 and48. As can readily be appreciated, rotation of the shafts 47 and 48 willresult in an opening and/or closing movement with respect to the blowmold halves 25 and 26 at the blow station 22. The shaft 48, as shown inFIG. 3, has its end supported in bearings 61 and 62. In a similarmanner, the other mold supporting mechanisms and their actuation areessentially the same as that described in detail with regard to station22 shown in FIGS. 3 and 4.

In the particular arrangement and position of the apparatus shown inFIGS. 1 and 2, two neck rings or finish mold supporting mechanisms,generally designated 63, are shown, one being positioned at the parisonforming station 17 and the other being positioned at the blow moldstation 21. These neck ring supporting mechanisms provide the means fortransferring and inverting formed parisons from the parison molds to theblow molds. Neck ring supporting units include a plurality of split neckrings or molds 64 (see FIGS. 5 and 6) and centrally positioned plungers65. Each individual neck mold has a plunger carried coaxially therewith,it being understood that in the mechanism shown on the drawings, fourneck rings and plunger units are carried by each invert mechanism.Furthermore, as will be later explained in more detail when consideringFIGS. 5 and 6, the neck ring supporting mechanism 63 is mounted to orcarried by a pair of spaced-apart invert arms 66 and 67. The invert arms66 and 67 are detachably connected to a horizontal spindle 68 by amounting bracket 69. The spindle 68 is provided with end bearings 70 and71. Adjacent the end bearing 71, the spindle 68 carries a pinion 72. Thepinion 72 is in mesh with a vertically extending rack 73 and throughreciprocation of the rack 73 the arms 66 and 67 will effect the transferof the parisons by their necks from the parison forming station 17 toblow station 22. Operating in a like manner, will be the neck ringsupport mechanism 63' at the blow station 21 and as shown in FIGS. 1 and2, is in the position where the transfer of the parison has beencompleted.

The transfer arms, for purposes of simplification, are designated withthe same reference numerals as those applied to the set of transfer arms66 and 67 which are in position at the parison station but are primed.As can be seen in viewing FIG. 2, the left-hand spindle 68' carries apinion 72' to which a rack 73' is in engagement and will effect therevert motion of the neck ring or mold support mechanism 63'. Operationof the racks 73 and 73' is through linkages 74 and 74'. The motors 15and 15', which are of the double acting or reciprocating fluid type,drive output shafts 75 and 75'. The output shafts 75 and 75' areconnected to cranks 76 and 76' which in turn are pivotally connected tothe lower ends of linkages 74 and 74'. As shown in FIG. 2, the crank 76extends upwardly and the position of the rack 73 is at its uppermostposition. The rack 73' is in its lowermost position and the crank 76' isextending vertically downward, it being understood that the motor 15',associated with the output shaft 75', will move the crank 76 in aclockwise direction to effectively revert the invert arm 66' from theblow mold station 21 to the parison mold station 17.

At the blow stations 21 and 22 there are provided bottom plate supportmembers 77 and 78. As will be appreciated, the apparatus is capable offorming containers of various heights and sizes, thus the blow moldswill be changed depending upon the configuration of the finished warethat is to be produced. With this in mind, it is necessary that thebottom plate for the blow mold, which remains in position at the blowstation, be capable of vertical adjustability. It should also beunderstood that the bottom plate is an item that may be replaced on itssupport by bottom plates of other sizes. The support members 77 and 78are of a generally conventional configuration and are of a style wherethe height of the support mechanism may be adjusted by rotation ofbeveled gears 79 and 80 in a conventional manner, as taught in the priorart. Beveled gears 79 and 80 normally will have cooperative beveledgears, not shown, which are hand-operable since this adjustment is madeat the time of the initial set-up of the machine. It is not somethingwhich varies during the operation of the machine in making ware.

At the parison forming station 17 there is shown a similar supportmember 81. The upper end of the member 81 is provided with a vacuumchamber 82. As best shown in FIGS. 5 and 6, the vacuum chamber 82 has atop wall 83 with an opening 84 formed therein. It should be pointed outthat the vacuum chamber 82 extends the full span of the plurality ofmold cavities that are present at the parison forming station and therewill be an opening 84 associated with each parison mold cavity. Abovethe opening 84, an upwardly extending annular member 85 is provided,with the member 85 having a downwardly and inwardly beveled inner wall86. The member 85, with its tapered wall 86 is adapted to cooperativelyengage or be engaged by a lower annular, tapered end 87 of plunger 65.The actual upper positioning of the chamber 82 is critical and mustcooperatively engage with the end 87 of the plunger during the initialportion of the parison forming cycle. When the invert arms 66 and 67 aremoved into the position shown in FIGS. 1 and 2, the top wall 83 ofvacuum chamber 82 will be at the position specifically illustrated inFIGS. 2 and 5, at which time the end 87 of the plunger 65 will engageannular member 85 on the top wall 83 of the chamber 82. The plunger 65has a vertical passageway 88 extending from the lower end to a positionapproximately half the length thereof. The plunger 65 is verticallypositionable within a plunger guide 89. A compression spring 90 biasesthe plunger 65 in a downward direction relative to the plunger guide 89.When, in the position shown in FIG. 5, the plunger is engaged with theannular member 85, the plunger will be in its uppermost position, atwhich time the passageway 88 will be in communication with vacuum in thevacuum chamber 82. The vacuum in passageway 88, through side ports 91,communicates with an annular chamber 92 within the plunger guide 89.Chamber 92 effectively provides for vacuum about the upper end of theplunger 65 in the neck ring area to provide a vacuum settle of the gobof molten glass around the tip of the plunger 65 and within the confinesof the neck ring or mold 64.

In the cycle for forming the parison after vacuum settle has beencompleted, the vacuum chamber 82 is lowered to the position shown inFIG. 6. At this time, vacuum may be discontinued in its supply to thechamber 82. The plunger 65, under the influence of the compressionspring 90, will move downwardly with a lower shoulder 93 engaging aninwardly extending annular shoulder 94 at the lower end of the plungerguide 89. The plunger guide 89 supports an air manifold 95 which extendsalong essentially the full length of the plunger guide 89. A source ofair under pressure is supplied to the manifold 95 through a pipe 96. Themanifold 95 has a series of openings 97 that communicate with individualpassageways 98 in plunger guide 89. The passageway 98, as shown in FIG.6, extends through and is in communication with the chamber within guide89 in which the plunger guiding function takes place. A passageway 99 inthe plunger 65 will come into alignment with passageway 98 when theplunger is in its fully retracted position, as illustrated in FIG. 6, atwhich time air under relatively low pressure will enter the passageway99 and enter the annular chamber 92, flow past the tip of the plunger 65and begin to expand molten glass by forming a bubble 100 which isgradually expanded until the molten glass touches all the walls of themold halves 19 and 20 and a bottom closing baffle 101. As the plungermoves to the position shown in FIG. 6, the vacuum ports 91 are coveredto effectively seal the guide chamber 92 from leakage through thepassage 88.

As shown in FIG. 2, the baffle 101 is carried by a support 102 whichwill effectively carry, in the present case, four individual baffles.The mechanism for mounting and moving the baffle support 102 is notshown, it being understood that baffles 101 must be positioned out ofalignment with the mold cavities at the time the cavity is being loadedwith a gob of molten glass and also the baffles must be positioned suchthat they do not interfere with the transfer of the formed parisons fromthe parison station to the blow mold stations.

The plunger guide 89 also carries an elongated cover 103 in generallyopposing relationship with respect to the manifold 95. The cover 103encloses a shaft 104. The shaft 104 is the neck mold opening and closingmechanism drive shaft, details of which are not shown. The shaft 104extends between and through the arms 66 and 67. The shaft will actuate amechanism within the arms 66 and 67 for spreading the neck molds torelease the neck of the parisons at the blow mold station. The shaft 104at one end carries a crank arm 105 to which a link 106 is pivotallyattached. The link 106 is connected to an output shaft 107 of a fluidmotor 108, with the motor 108 being mounted to a bracket 109 fixed tothe side of the arm 66. Actuation of the motor 108 will result inrotation of the shaft 104, it being understood that rotation of theshaft 104 will effectively open or close the neck molds or neck rings ina pre-selected sequence dictated by the forming cycle.

After the parisons are transferred from the parison forming station 17to either of the blow mold stations 21 or 22, the neck molds or ringsare opened, releasing the parison so that it may reheat and run underthe influence of gravity while being suspended by the finish or the neckportion. Then blowheads, designated 110 and 110', will move intooverlying relationship to the upper neck of the parisons to apply airunder pressure to the interior of the parison to expand it into itsfinal shape determined by the shape of the cavity in the blow mold. Theblowheads 110 and 110' are shown in their "parked" position forconvenience, it being understood that operation of a verticallypositioned motor 111 or 111' will drive a rack 112 or 112' in mesh witha pinion 113 or 113' to drive a "four-bar" linkage 114 or 114' to whichthe blowheads 110 or 110' are mounted by a support rack 115 or 115'.After the bottles have been fully formed, the molds, for example at blowstation 22, will be moved apart leaving the blown containers sitting onbottom plates 116, at which time take-out mechanisms generallydesignated 117 will be operated to take the formed bottles from thebottom plates 116 to a position which is clear of the forming machinewhere the ware is then placed on a cooling dead plate 118 (see FIG. 20).The take-out mechanism 117 consists of an elongated head 119 whichcarries a plurality of, in this case four, tongs 120 which effectivelygrip the blown containers by their necks beneath the finish. The head119 is supported intermediate its length by a pivot shaft 121 whichextends through a transfer arm 122. The shaft 121, within the confinesof the transfer arm 122 which in actual practice is a hollow housing,carries a sprocket. This sprocket supports a chain 123 which extendsaround a second sprocket 124 carried by a pivot shaft 125. The shaft 125is driven by a pinion 126 which is in mesh with a verticallyreciprocable rack 127. The rack 127 is connected at its lower end to alink 128, with the lower end of the link being connected to a crank 129carried by a drive shaft 130. The shaft 130 is the output shaft of areciprocatory fluid motor 131, of substantially the same generalconfiguration as motors 15 or 15'. Thus it can be seen thatreciprocation of the rack 127 will move the ware from the blow station22 to the position shown in FIG. 3 while maintaining the ware in anupright attitude. The tongs are opened and closed in a conventionalmanner and will receive signals from the overall timing system of theforming machine.

The foregoing description sets forth in some detail the mechanisms whichare capable of carrying out the process of the invention.

With reference to FIGS. 7-21, the forming cycle or process carried outby the apparatus will be described. FIG. 7 shows the beginning point inthe cycle when the parison mold halves 19 and 20 are closed about theneck molds or neck rings 64 and the neck ring support mechanism 63 is inthe parison forming position. The vacuum chamber support member 81 is inelevated position with the vacuum chamber 82 communicating with theinterior passage 88 in the plunger 65. At this point in the formingcycle, a gob 132 of molten glass is about to enter the open upper end ofthe parison mold. In FIG. 8, the gob has entered the mold and the vacuum82 has settled the gob 132 about the raised plunger or neck pin 65. FIG.9 illustrates the next sequence of events and is similar to FIG. 6,wherein the support member 81 is lowered thus permitting the plunger 65to retract under the influence of the spring 90, with air within themanifold chamber 95 beginning to expand the gob 132 by forming thebubble of air 100 therein. At this point in time, the baffle 101 isseated to close the open upper end of the parison mold. Turning now toFIG. 10, the bubble 100 has increased in size due to the air underpressure from the manifold 95 which, it must be remembered, isrelatively low in pressure compared with the pressures that have beenused in the past to develop the parison or, as termed in the art,"counter-blowing the parison". This low pressure air in the manifold 95is continued until the parison is fully formed, as shown in FIG. 11.When the parison is completely formed, the baffle 101 is raised to theposition shown in FIG. 12 and the parison mold halves 19 and 20 areopened, with the completed parison, designated 133, extending generallyvertically with respect to the neck rings 64. Air under pressure fromthe manifold 95 is maintained above atmospheric within the interior ofthe parison 133 to help support the parison. The neck rings 64, aspreviously stated, are supported by the mechanism generally designated63 which in turn is supported by the invert arm 66. It should beunderstood that there is another invert arm 67, as shown in FIG. 1,associated with the supports 63. As shown in FIG. 13, the invert arm 66will swing about the horizontal axis of the spindle 68 to transfer theparisons to the blow molding station 22. In FIG. 14, the parison is inits midpoint in the invert transfer from the parison station 17 to theblow molding station 22. Here again the low pressure air is maintainedwithin the interior 100 of the parison 133. As a matter of fact, it ispossible to continue slight expansion of the parison during the invertoperation which takes place in the sequence of FIGS. 13, 14 and 15 if itis determined to be desirable to effect the proper configuration of theparison and the temperature thereof.

After the parison has arrived at the blow molding station 22 illustratedin FIG. 15, the parison will have its outer skin reheated due to thetemperature of the glass within the interior of the parison and the airunder soft pressure will have been discontinued at this point in timeand the parison will sag from its own weight under the influence ofgravity. The blow mold halves 25 and 26 are closed relative to theparison and the bottom plate 116, assuming the position illustrated inFIG. 16. The neck rings are opened and the parison is released so as tobe suspended by its neck from the upper surface of the blow mold halves25 and 26 at the blow station 22. This is specifically illustrated inFIG. 16. The invert arm 66 is reverted to the parison station 17. Whilethe parison 133 continues to run and reheat, a blowhead 110 is broughtinto overlying relationship with respect to the blow mold halves 25 and26 and air under pressure introduced through the blowhead 110 willexpand the parison to the final bottle shape, as shown in FIG. 17. Theblowhead 110 will then be moved upward and away from the blow moldingstation 22 at which time, as illustrated in FIG. 19, the mold halves 25and 26 are moved apart leaving the blown container resting on the bottomplate 116. The neck-grasping tongs 120 engage the finish of thecontainer and move the container from the bottom plate 116 to the uppersurface or cooling dead plate 118, see FIG. 20, through which air passesto set-up the bottom of the container and cool it sufficiently to permitit to be handled through the annealing process. The tongs 120 will open,releasing the bottle to the cooling dead plate 118. In the propersequence of events, the container sitting on the dead plate 118 will bemoved by a pusher bar 134 which pushes the container from the dead plateonto the upper surface of a conveyor generally designated 135 in FIG.21. This completes one full cycle in the formation of a container fromthe time the gob is fed to the parison mold until such time as acompletely formed glass container or bottle is moved to a conveyor whichwill carry the container away from the forming machine area to aposition where it will be transferred to an annealing lehr.

As can be seen from the foregoing, the process set forth herein and asgenerally illustrated in FIGS. 7-21, the counterblowing of the parisonmay take place sooner than in those situations in the prior art whereinthe parison is settled around the neck pin or plunger by application ofair under pressure above the gob, due to the fact that by using vacuumthe parison is settled more quickly. The counterblow, being soft,extends the time in which the parison is being counterblown. The term"soft" being synonymous with low pressure. The early application of thesoft counterblow has the benefits of permitting a hotter glass gobtemperature and by having the neck ring invert or transfer unit in whicha positive internal pressure is maintained within the parison to preventcollapse during the invert, assures a more uniformly distributed radialglass wall dimension. A longer controlled reheat also contributes to theend result of a container which has very uniform glass walldistribution. This improved distribution permits a substantial reductionin glass weight without any loss of container strength.

We claim:
 1. The method of forming glass containers by the "blow andblow" process wherein a gob of glass is delivered to a parison and neckmold cavity and the gob is settled in the neck mold by vacuum andimmediately after being settled is counterblown in the parison mold tothereby form a parison with the glass forming the parison having beencontinuously worked from the time of gob delivery until the parison iscompletely formed and, with the parison mold being removed from theparison, the parison then being inverted and transferred from theparison forming position to a blow or final mold where the parison isexpanded into final form, the improvement comprising:maintaining acondition of above atmospheric pressure within the interior of theformed parison at a sufficient level to prevent collapse of the parisonduring the transfer and inversion thereof to the blow or final mold; andreleasing the pressure from the interior of the parison after transferto the blow mold is completed, whereby a glass container of a givencapacity may be formed with less glass, be of more uniform wallthickness and have improved strength.
 2. The method of claim 1 whereinsaid step of maintaining pressure within the unconfined parison duringtransfer comprises sealing the interior of the parison after expansionin the parison mold and with the pressure therein.
 3. The method ofclaim 1 wherein said pressure maintaining step comprises introducing airunder pressure to the interior of the unconfined parison during theentire invert and transfer interval.
 4. The method of forming glasscontainers by the "blow and blow" process wherein a gob of glass isdelivered to a parison and neck mold cavity and the gob is settled inthe neck mold by vacuum and immediately after being settled iscounterblown in the parison mold to thereby form a parison with theglass forming the parison having been continuously worked from the timeof gob delivery until the parison is completely formed and, with theparison mold being removed from the parison, the parison then beinginverted and transferred from the parison forming position to a blow orfinal mold where the parison is expanded into final form, theimprovement comprising:maintaining a condition of above atmosphericpressure within the interior of the formed parison at a sufficient levelto prevent collapse of the parison during the transfer and inversionthereof to the blow or final mold; releasing the pressure from theinterior of the parison after transfer to the blow mold is completed;and permitting the parison to elongate and the interior thereof reheatthe surface glass for a time approximately equal to one-fourth the totalforming cycle, whereby a glass container of a given capacity will beformed with less glass, be of more uniform wall thickness and haveimproved strength.
 5. The method of claim 4 wherein said step ofmaintaining pressure within the unconfined parison during transfercomprises sealing the interior of the parison after expansion in theparison mold and with the pressure therein.
 6. The method of claim 4wherein said pressure maintaining step comprises continuing the airunder pressure to the interior of the unconfined parison during aportion of the invert and transfer interval.
 7. The method of formingglass containers comprising the steps of:forming a smaller charge ofmolten glass at an elevated temperature; loading the charge into aclosed, inverted parison mold, neck mold and central plungercombination; immediately applying a vacuum to the neck mold afterloading of the charge in the mold to thereby settle the charge intoclose contact with the plunger and neck mold; closing the upper end ofthe parison mold with a baffle; withdrawing the plunger from the neckmold without removing substantial heat by the plunger from the glasscharge; applying a low pressure air to the interior of the charge pastthe withdrawn plunger; continuing the low pressure air application for atime sufficient to complete a soft counterblow of the charge into aparison defined by the interior of the parison mold; opening the parisonmold and removing the baffle therefrom; maintaining the low pressure airwithin the interior of the parison at a sufficient level to preventcollapse of the parison; transferring the parison by an invert motionfrom the parison mold to a blow mold while maintaining the low pressureair within the parison to prevent collapse thereof during invert;permitting the inverted parison to run under the combined influence ofgravity and maintaining low pressure air; closing the blow mold aboutthe formed parison and permitting the parison to reheat and run whilesupported in the blow mold for a period of time equal to approximatelyone-third the full forming cycle time; expanding the parison within theblow mold; and removing the finished light-weight container therefrom.8. Method of forming lightweight glass containers by the blow and blowprocess wherein a gob or charge of glass at an elevated temperature isdelivered to a parison mold with a neck mold therebeneath and vacuum isapplied to the neck mold to settle the charge around a neck pin in theneck mold to form the glass container finish, the improvement comprisingsoftly counterblowing the charge in the parison mold to the shape of theparison mold and end closing baffle without creating a compacting forcebetween the charge and the mold so as to avoid forming a parison whichis self-supporting and thereby maintaining the parison with a relativelythin skin, maintaining a degree of pressure within the hollow parison tokeep the parison with included air sufficiently supported to betransferred without collapse; and inverting and transferring the formedparison to a blow mold.
 9. The method of claim 8 wherein the step ofsoftly counterblowing is effected with a pressure of less than 10 psi.10. The method of claim 8 wherein the counter-blowing pressure is in therange of 3-10 psi.
 11. The method of claim 8 wherein said step ofmaintaining pressure within the unconfined parison during transfercomprises sealing the interior of the parison after expansion in theparison mold with the pressure therein.
 12. The method of claim 8wherein said pressure maintaining step comprises continuing the airunder pressure to the interior of the parson unconfined during at leasta portion of the invert and transfer interval.
 13. The method of forminglight-weight glass containers comprising the steps of:forming a chargeof molten glass at an elevated temperature; loading the charge into aclosed, inverted parison mold, neck mold and central plungercombination; immediately applying a vacuum to the neck mold afterloading of the charge in the mold to thereby settle the charge intoclose contact with the plunger and neck mold; closing the upper end ofthe parison mold with a baffle; withdrawing the plunger from the neckmold without removing substantial heat from the glass charge;immediately applying a low pressure air to the interior of the chargepast the withdrawn plunger; continuing the low pressure air applicationfor a time sufficient to complete a soft counterblow of the charge intoa parison defined by the interior of the parison mold; opening theparison mold and removing the baffle therefrom; applying a low pressure"puff" of air to the interior of the parison; maintaining the puff airwithin the parison to prevent collapse thereof during invert;transferring the parison by inverting the parison mold to a blow mold;closing the blow mold about the formed parison; permitting the invertedparison to reheat and run under the combined influence of gravity andpuff pressure while supported in the blow mold for a period of time ofone-third to one-fourth the full forming cycle time; expanding theparison within the blow mold; and removing the finished light-weightcontainer therefrom.